Electronic device and method for fabricating the same

ABSTRACT

An electronic device has an element formed in the chip region of a substrate, a plurality of interlayer insulating films formed on the substrate, a wire formed in the interlayer insulating films in the chip region, and a plug formed in the interlayer insulating films in the chip region and connecting to the wire. A seal ring extending through the plurality of interlayer insulating films and continuously surrounding the chip region is formed in the peripheral portion of the chip region. A stress absorbing wall extending through the plurality of interlayer insulating films and discretely surrounding the seal ring is formed outside the seal ring.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. application Ser. No.12/184,697, filed on Aug. 1, 2008, which is a Divisional of U.S.application Ser. No. 11/223,943, filed Sep. 13, 2005, now U.S. Pat. No.7,417,304, claiming priority of Japanese Application No. 2004-277087,filed Sep. 24, 2004, the entire contents of each of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to an electronic device having a seal ringformed to surround a chip region and a mechanism for protecting the sealring and to a method for fabricating the same.

An electronic device such as a semiconductor device is typically formedby arranging a large number of IC circuits each composed of a pluralityof elements and having a specified function as a matrix on asemiconductor wafer made of, e.g., silicon or the like.

A large number of chip regions arranged in the wafer are separated fromeach other by scribe regions (scribe lines) provided in a grid-likeconfiguration. After the large number of chip regions are formed in asingle wafer through a semiconductor fabrication process, the wafer isdiced into individual chips along the scribe regions so thatsemiconductor devices are formed.

When the wafer is diced to be separated into the individual chips,however, the portions of the chip regions which are adjacent to thescribe lines receive mechanical impact, which may cause local cracks orchippings in the cross sections of the individual chips, i.e.,semiconductor devices into which the wafer has been separated.

As a solution to the problem, Japanese Laid-Open Patent Publication No.2001-23937 proposes a technology which provides a seal ring as aring-shaped protective wall around each of the chip regions to preventthe propagation of a crack in the chip region during dicing.

FIG. 32 shows a cross-sectional structure of a conventionalsemiconductor device (that has been embedded in a wafer) having a sealring.

As shown in FIG. 32, a seal ring 4 extending through the multilayerstructure and continuously surrounding the chip region 2 is formed inthe portion of the multilayer structure consisting of the plurality ofinterlayer insulating films 5 to 10 which is located in the peripheralportion of the chip region 2. The seal ring 4 is formed by alternatelyusing a mask for wire formation and a mask for via formation, as shownin, e.g., Japanese Laid-Open Patent Publication No. 2001-23937.Specifically, the seal ring 4 is composed of: a conductive layer 30formed in the substrate 1, a seal via 31 formed in the interlayerinsulating film 5 and connecting to the conductive layer 30; a seal wire32 formed in the interlayer insulating film 6 and connecting to the sealvia 31; a seal via 33 formed in the interlayer insulating film 7 andconnecting to the seal wire 32; a seal wire 34 formed in the interlayerinsulating film 8 and connecting to the seal via 33; a seal via 35formed in the interlayer insulating film 9 and connecting to the sealwire 34; and a seal wire 36 formed in the interlayer insulating film 10and connecting to the seal via 35. In the present application, theportions of the seal ring formed by using the mask for wire formationwill be termed seal wires and the portions of the seal ring formed byusing the mask for via formation will be termed seal vias.

As also shown in FIG. 32, a passivation film 11 is further provided overthe multilayer structure consisting of the plurality of interlayerinsulating films 5 to 10 and provided with the wires (22, 24, and 26)and with the vias (21, 23, and 25). The passivation film 11 has anopening formed over the wire 26 and a pad 27 connecting to the wire 26is formed in the opening.

SUMMARY OF THE INVENTION

In the conventional semiconductor device, however, even though a crackor impact that has occurred during the dicing of a wafer can beprevented from propagating toward the inner portion of the chip regionby using the seal ring, a crack or flaw occurs in a part of the sealring. Accordingly, the seal ring cannot sufficiently exert the functionof preventing the ingression of moisture, movable ions, and the likeinto the region surrounded by the seal ring, which is one of theintrinsic functions of the seal ring.

Since the seal ring has been provided continuously in the peripheralportion of the chip region, there are cases where the portion of theseal ring that has been destroyed through the absorption of the crack orimpact may be left protruding from the end portion of one of individualsemiconductor devices (semiconductor chips) into which the wafer hasbeen separated by dicing. When packaging is performed with respect tothe semiconductor device in such a condition, the residue of the sealring comes into contact with a bonding wire and causes a defectiveproduct.

To prevent an increase in wire-to-wire capacitance resulting from theminiaturization of a semiconductor device and a wire connecting thereto,i.e., a reduction in the processing speed of the semiconductor device, atechnology which prevents the increase in wire-to-wire capacitance byusing an interlayer insulating film with a low dielectric constant hasbeen developed.

However, since the interlayer insulating film with a low dielectricconstant is typically low in mechanical strength, the resistance of theinterlayer insulating film with a low dielectric constant to a stressoccurring during dicing is less sufficient than the resistance of amaterial that has been used conventionally for an interlayer insulatingfilm. Accordingly, the interlayer insulating film with a low dielectricconstant is more susceptible to damage during dicing. As a result, ithas been becoming increasingly difficult to perform both of the functionof preventing the propagation of a crack or the like that has occurredduring dicing and the function of preventing the ingression of moisture,movable ions, and the like into the chip region from the outside thereofby using only a seal ring, as has been performed conventionally.

In view of the foregoing, it is therefore an object of the presentinvention to prevent a crack, a flaw, or the like that has occurred inthe side surface of each of chips during the division of a wafer intothe individual chips (semiconductor devices) by dicing from reaching aseal ring and causing the destruction thereof in order to preventfurther propagation of the crack, flaw, or the like into the chip regionand thereby prevent the degradation of the moisture resistance andreliability of an electronic device.

To attain the object, the electronic device according to the presentinvention comprises: an element formed in a chip region of a substrate;a multilayer structure composed of a plurality of interlayer insulatingfilms formed on the substrate; a wire formed in at least one of theplurality of interlayer insulating films in the chip region; a plugformed in at least one of the plurality of interlayer insulating filmsin the chip region and providing a connection between the element andthe wire or between the individual wires; a seal ring formed in aportion of the multilayer structure composed of the plurality ofinterlayer insulating films which is located in a peripheral portion ofthe chip region to extend through the multilayer structure andcontinuously surround the chip region; and a stress absorbing wallformed in a portion of the multilayer structure composed of theplurality of interlayer insulating film which is located outside theseal ring to extend through the multilayer structure and discretelysurround the seal ring.

In the electronic device according to the present invention, the stressabsorbing wall is formed to surround the seal ring so that a crack,stress, or the like that has occurred during the dicing of a wafer isblocked by the stress absorbing wall before reaching the seal ring. Thiseliminates a situation where the seal ring is cracked or destroyed andthereby prevents the impairment of the function of reliably protectingthe inner portion of the chip region, which is one of the intrinsicfunctions of the seal ring.

In the electronic device according to the present invention, the stressabsorbing wall discretely surrounds the seal ring, i.e., the individualcomponents of the stress absorbing wall are arranged discretely andindependently of each other along a direction in which the seal ringextends. Even though any of the individual components is damaged anddestroyed by the crack or the like during the dicing of the wafer, thereis no such situation that the destruction of the stress absorbing wallis enlarged along the direction in which the seal ring extends. That is,since the individual components of the stress absorbing wall areindependent of each other, it becomes possible to prevent a componentadjacent to a destroyed component from coming off as a result of beingpulled thereby. By reducing the size of each of the components of thestress absorbing wall, it also becomes possible to prevent a situationwhere the damaged component is left protruding from the end portion ofone of individual semiconductor devices (semiconductor chips) into whichthe wafer has been separated by dicing. In other words, the damagedcomponent is sufficiently small in size so that it comes off from thechip relatively easily

In the electronic device according to the present invention, the stressabsorbing walls in a double or higher-order multiple structure arepreferably surrounding the seal ring.

In the arrangement, even though the crack, impact, or the like that hasoccurred during dicing is not absorbed completely by that one of thestress absorbing walls provided in a multiple structure which is at aposition closest to the diced portion (the portion of the scribe regionwhich is actually cut by the blade of a dicing system) of the wafer andpropagates toward the inner portion of the chip region, at least oneother stress absorbing wall that has been formed internally of that oneof the stress absorbing wall closest to the diced portion can preventfurther propagation of the crack, impact, or the like toward the innerportion of the chip region. As a result, the crack, impact, or the likethat has occurred during dicing is blocked before reaching the seal ringso that the seal ring is not cracked nor destroyed. Accordingly, thefunction of reliably protecting the inner portion of the chip region,which is performed by the seal ring, is not impaired.

When the stress absorbing walls in a double or higher-order multiplestructure are surrounding the seal ring, gap portions between respectivediscrete portions of each of the stress absorbing walls in the double orhigher-order multiple structure are preferably not aligned in rows.

In the arrangement, even though the crack, impact, or the like that hasoccurred during dicing is not blocked by that one of the stressabsorbing walls provided in a multiple structure which is at theposition closest to the diced portion of the wafer and propagates towardthe inner portion of the chip region by passing through the discreteportions of the stress absorbing walls (the portions of the stressabsorbing walls which are located between the individual componentsthereof), the crack, impact, or the like that has not been blocked bythe stress absorbing wall closest to the diced portion of the wafer isblocked by another stress absorbing wall located internally thereofbecause the gap portions of the stress absorbing wall closest to thediced portion of the wafer and those of the stress absorbing walllocated internally thereof are not aligned in rows in a directionperpendicular toe the direction in which the seal ring extends. In otherwords, the respective portions composing the individual stress absorbingwalls in a multiple structure are arranged with no space therebetween toform a whole entity when the chip region is viewed from the dicedportion of the wafer. The arrangement allows reliable prevention of thepropagation of the crack, impact, or the like from the diced portion ofthe wafer toward the inner portion of the chip region. As a result, thecrack, impact, or the like that has occurred during dicing can beblocked before reaching the seal ring so that the seal ring is notcracked nor destroyed. Accordingly, the function of reliably protectingthe inside of the chip region, which is performed by the seal ring, isnot impaired.

When the stress absorbing walls in a double or higher-order multiplestructure are surrounding the seal ring, each of components of the oneof the stress absorbing walls in the double or higher-order multiplestructure which is formed at a position most distant from the seal ringpreferably has a shorter length along a direction in which the seal ringextends than each of components of the other stress absorbing wall orwalls.

In the arrangement, even though the crack, impact, or the like that hasoccurred during dicing is not completely absorbed by that one of thestress absorbing walls provided in a multiple structure which is at theposition closest to the diced portion of the wafer and propagates towardthe inner portion of the chip region, at least one other stressabsorbing wall that has been formed internally of the stress absorbingwall closest to the diced portion of the wafer can prevent furtherpropagation of the crack, impact, or the like toward the inner portionof the chip region. In addition, since each of the components of thestress absorbing wall at the position closest to the diced portion ofthe wafer, i.e., at the position most distant from the seal ring hasshorter length, the crack, impact, or the like that has occurred duringdicing can be finely distributed and absorbed. As a result, theingression of the crack, impact, or the like that has occurred duringdicing can be prevented before it reaches the seal ring so that the sealring is not cracked nor destroyed. Accordingly, the function of reliablyprotecting the inner portion of the chip region, which is performed bythe seal ring, is not impaired. Since each of the components of thestress absorbing wall is smaller in size, even though one of thecomponents receives the crack, impact, or the like during dicing and isdestroyed thereby, the component easily comes off from the semiconductordevice (one of the individual semiconductor chips into which the waferhas been separated by dicing). This prevents a situation where thedestroyed component is left protruding from the end portion of thesemiconductor chip after dicing and thereby eliminates a defectiveproduct resulting from the contact between the residue of the stressabsorbing wall and a bonding wire when packaging is performed withrespect to the semiconductor chip.

In the electronic device according to the present invention, each of theseal ring and the stress absorbing wall may also be composed of at leastone of W, Al, and Cu.

A method for fabricating an electronic device according to the presentinvention is a method for fabricating an electronic device comprising anelement formed in a chip region of a substrate, a multilayer structurecomposed of a plurality of interlayer insulating films formed on thesubstrate, a wire formed in at least one of the plurality of interlayerinsulating films in the chip region, a plug formed in at least one ofthe plurality of interlayer insulating films in the chip region andproviding a connection between the element and the wire or between theindividual wires, a seal ring formed in a portion of the multilayerstructure composed of the plurality of interlayer insulating films whichis located in a peripheral portion of the chip region to extend throughthe multilayer structure and continuously surround the chip region, anda stress absorbing wall formed in a portion of the multilayer structurecomposed of the plurality of interlayer insulating film which is locatedoutside the seal ring to extend through the multilayer structure anddiscretely surround the seal ring. Specifically, the method comprisesthe steps of: forming, in one of the plurality of interlayer insulatingfilms, a first depressed portion to be filled with the plug or the wire,a second depressed portion to be filled with a part of the seal ring,and a third depressed portion to be filled with a part of the stressabsorbing wall; filling a conductive film in each of the first, second,and third depressed portions to form the plug or the wire, the part ofthe seal ring, and the part of the stress absorbing wall; and forming aprotective film on the multilayer structure composed of the plurality ofinterlayer insulating films provided with the wire, the plug, the sealring, and the stress absorbing wall.

Since the method for fabricating an electronic device according to thepresent invention is a method for fabricating the electronic deviceaccording to the present invention that has been described above, themethod can achieve the same effects as achieved by the electronic deviceaccording to the present invention that has been described above.

Thus, according to the present invention, the stress absorbing wall isprovided to discretely surround the seal ring in the electronic deviceincluding the chip region and the seal ring provided in the peripheralportion of the chip region and surrounding elements, a wiring layer, andthe like in the chip region. Alternatively, the stress absorbing wallhaving such a structure may also be stress absorbing walls in a doubleor higher-order multiple structure which are surrounding the seal ring.In that case, the respective gap portions of the individual stressabsorbing walls in a double or higher-order multiple structure arepreferably not aligned in rows and/or that one of the stress absorbingwalls which is most distant from the seal ring is preferably composed ofa plurality of portions smaller in size than the portions of the otherstress absorbing wall or walls.

Since the characteristic features of the present invention describedabove allow a crack, flaw, or the like caused by dicing in the waferwhen the individual chips (semiconductor devices) are collected from thewafer to be blocked by the stress absorbing wall or walls in a single,double, or higher-order multiple structure before it reaches the sealring, the destruction of the seal ring and the resulting destruction ofthe chip region serving as the semiconductor device can be presented. Asa result, it becomes possible to prevent the degradation of the moistureresistance and reliability of the semiconductor chip.

Thus, the present invention relates to an electronic device having aseal ring formed to surround the chip region and a mechanism forprotecting the seal ring and is extremely useful since it achieves theeffect of allowing the seal ring to retain the function of reliablyprotecting the inner portion of the chip region by blocking a crack,stress, or the like that has occurred during dicing by using a stressabsorbing wall.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a part of a wafer provided with anelectronic device according to a first embodiment of the presentinvention;

FIG. 2 is a cross-sectional view taken along the line A-A′ of FIG. 1;

FIG. 3 is a plan view obtained by enlarging the vicinity of the lineA-A′ of FIG. 1;

FIG. 4 is a cross-sectional view illustrating the individual processsteps of a method for fabricating an electronic device according to thefirst embodiment;

FIG. 5 is a cross-sectional view illustrating the individual processsteps of the method for fabricating the electronic device according tothe first embodiment;

FIG. 6 is a cross-sectional view illustrating the individual processsteps of the method for fabricating the electronic device according tothe first embodiment;

FIG. 7 is a cross-sectional view illustrating the individual processsteps of the method for fabricating the electronic device according tothe first embodiment;

FIG. 8 is a post-dicing cross-sectional view taken along the line A-A′of FIG. 1;

FIG. 9 is a post-dicing plan view obtained by enlarging the vicinity ofthe line A-A′ of FIG. 1;

FIG. 10 is a cross-sectional view showing the electronic device (afterdicing) according to the first embodiment, which has been mounted on alead frame;

FIG. 11 is a cross-sectional view of the end portions of pre-dicingsemiconductor devices according to a comparative example.

FIG. 12 is a plan view of the end portions of the pre-dicingsemiconductor devices according to the comparative example;

FIG. 13 is a cross-sectional view of the ends portion of the post-dicingsemiconductor devices according to the comparative example.

FIG. 14 is a plan view of the end portions of the post-dicingsemiconductor devices according to the comparative example;

FIG. 15 is a cross-sectional view showing the semiconductor device(after dicing) according to the comparative example, which has beenmounted on a lead frame;

FIG. 16 is a plan view showing a part of a wafer provided with anelectronic device according to a second embodiment of the presentinvention;

FIG. 17 is a cross-sectional view taken along the line B-B′ of FIG. 16;

FIG. 18 is a plan view obtained by enlarging the vicinity of the lineB-B′ of FIG. 16;

FIG. 19 is a cross-sectional view illustrating the individual processsteps of a method for fabricating an electronic device according to thesecond embodiment;

FIG. 20 is a cross-sectional view illustrating the individual processsteps of the method for fabricating the electronic device according tothe second embodiment;

FIG. 21 is a cross-sectional view illustrating the individual processsteps of the method for fabricating the electronic device according tothe second embodiment;

FIG. 22 is a cross-sectional view illustrating the individual processsteps of the method for fabricating the electronic device according tothe second embodiment;

FIG. 23 is a plan view showing a part of a wafer provided with anelectronic device according to a third embodiment of the presentinvention;

FIG. 24 is a cross-sectional view taken along the line C-C′ of FIG. 23;

FIG. 25 is a plan view obtained by enlarging the vicinity of the lineC-C′ of FIG. 23;

FIG. 26 is a plan view showing a part of a wafer provided with anelectronic device according to a fourth embodiment of the presentinvention;

FIG. 27 is a cross-sectional view taken along the line D-D′ of FIG. 26;

FIG. 28 is a plan view obtained by enlarging the vicinity of the lineD-D′ of FIG. 26;

FIGS. 29A to 29F are cross-sectional views of variations of a seal ringstructure according to each of the embodiments of the present invention;

FIGS. 30A to 30C are plan views of variations of the seal ring structureaccording to each of the embodiments of the present invention;

FIGS. 31A to 31C are plan views of variations of the seal ring structureaccording to each of the embodiments of the present invention; and

FIG. 32 is a cross-sectional view of a conventional semiconductordevice.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, the individual embodiments of the presentinvention will be described herein below.

A first characteristic feature of the present invention is that each ofa seal ring and a stress absorbing wall is formed in the same step inwhich a wiring structure is formed. In addition, the individualcomponents of the stress absorbing wall are arranged discretely andindependently of each other along a direction in which the seal ringextends. Accordingly, even though any of the components is damaged anddestroyed by a crack or the like that has occurred during the dicing ofa wafer, there is no such situation that the destruction of the stressabsorbing wall is enlarged along the direction in which the seal ringextends. Since the individual components of the stress absorbing wallare independent of each other, it becomes possible to prevent acomponent adjacent to the destroyed one from coming off as a result ofbeing pulled thereby. It also becomes possible to prevent a situationwhere the damaged component is left protruding from the end portion ofone of individual semiconductor devices (semiconductor chips) into whichthe wafer has been separated by dicing (a first embodiment).

A second characteristic feature of the present invention is that stressabsorbing walls in a double or higher-order multiple structure areprovided. In the arrangement, even though the crack, impact, or the likecannot be absorbed completely by one of the stress absorbing walls, itcan be absorbed by another stress absorbing wall. As a result, itbecomes possible to prevent the crack, impact, or the like from reachingthe seal ring (a second embodiment).

A third characteristic feature of the present invention is that gapportions between the respective discrete portions of the stressabsorbing walls in a double or higher-order multiple structure are notaligned in rows. As a result, the respective portions composing theindividual stress absorbing walls in a multiple structure are arrangedwith no space therebetween to form a whole entity when the chip regionis viewed from the diced portion of the wafer. Therefore, compared withthe cases where the stress absorbing wall is in a single structure andwhere the respective gap portions of the individual stress absorbingwalls in a double or higher-order multiple structure are aligned in rows(i.e., in the case where the respective plan configurations of theindividual stress absorbing walls are analogous), the seal ring and thechip region can be protected more reliably (a third embodiment).

A fourth characteristic feature of the present invention is that thecomponents of that one (the outermost stress absorbing wall) of thestress absorbing walls in a double or higher-order multiple structurewhich is formed at a position most distant from the seal ring areshorter in length along the direction in which the seal ring extendsthan the components of the other stress absorbing wall or walls. In thearrangement, the outermost stress absorbing wall allows the crack,impact, or the like that has occurred during dicing to be finelydistributed and absorbed so that the propagation thereof is blockedsuccessfully before it reaches the seal ring. As a result, each of theseal ring and the chip region can be protected. Since the components ofthe outermost stress absorbing wall are small in size, even though anyof the components receives the crack, impact, or the like during dicingand is destroyed thereby, the component easily comes off from thesemiconductor device (one of the individual semiconductor chips intowhich the wafer has been separated by dicing). This makes it possible toprevent a situation where the destroyed component is left protrudingfrom the end portion of the semiconductor chip after dicing andeliminate a defective product resulting from the contact between theresidue of the stress absorbing wall and a bonding wire when packagingis performed with respect to the semiconductor chip (a fourthembodiment).

Embodiment 1

An electronic device according to a first embodiment of the presentinvention and a method for fabricating the same will be described withreference to the drawings.

FIG. 1 is a plan view showing a part of a wafer provided with anelectronic device (a semiconductor device having a seal ring singlysurrounding a chip region) according to the first embodiment.

As shown in FIG. 1, a plurality of chip regions 102, each of which is toserve as a semiconductor device, are arranged in a wafer 101 serving asa semiconductor substrate represented by, e.g., a silicon substrate orthe like. Each of the chip regions 102 is provided with an IC(integrated circuit) composed of a plurality of elements and having aspecified function. The individual chip regions 102 are defined byscribe regions 103 provided in a grid-like configuration.

Each one of the semiconductor devices (i.e., each one of thesemiconductor chips) is comprised herein of: a chip region 102 in whichthe IC circuit composed of the plurality of elements and having thespecified function; a seal ring 104 provided in the peripheral portionof the chip region 102 to surround the chip region 102; and a stressabsorbing wall 105 according to the present invention which is providedoutside the seal ring 104 to discretely surround the seal ring 104. Thewafer 101 thus formed with the plurality of semiconductor devices isdiced along the scribe regions 103 after the completion of theindividual chips so that it is separated into the individualsemiconductor devices.

FIG. 2 is a cross-sectional view (cross-sectional view of the endportions of the semiconductor devices including seal ring portionspositioned in the peripheral portions of the chip regions 102 and, morespecifically, of wiring structures in the chip regions 102 and thestructures of the seal rings 104) taken along the line A-A′ of FIG. 1.FIG. 3 is a plan view obtained by enlarging the vicinity of the lineA-A′ of FIG. 1. Each of FIGS. 2 and 3 shows the respective end portionsof the pair of chip regions 102 with the scribe region 103 interposedtherebetween.

As shown in FIGS. 2 and 3, each of the semiconductor devices prior todicing is composed of the chip region 102 and the scribe region 103. Theseal ring 104 is formed in the portion of the chip region 102 which isadjacent to the boundary with the scribe region 103, while the stressabsorbing wall 105 is formed outside the seal ring 104 (in the portionof the scribe region 103 which is adjacent to the boundary with the chipregion 102).

A description will be given herein below to the method for fabricatingthe semiconductor device having the structure shown in FIGS. 2 and 3with reference to FIGS. 4, 5, 6, and 7.

First, as shown in FIG. 4, active layers 110 composing elements such asa transistor are formed in the chip regions 102 of the wafer 101(hereinafter referred to as the substrate 101), while conductive layers120 similarly constituted to the active layers 110 are formed in theperipheral portions (the regions to be formed with the seal rings whichare adjacent to the scribe region 103) of the chip regions 102 of thesubstrate 101.

Next, a first interlayer insulating film 106 is deposited on thesubstrate 101. Then, via holes 106 a for forming first vias 111 (seeFIG. 6) are formed in the portions of the first interlayer insulatingfilm 106 located in the individual chip regions 102 by using alithographic technology and a dry etching technology, while trench-likedepressed portions 106 b for forming first seal vias 121 (see FIG. 6)are formed in the portions of the first interlayer insulating film 106located in seal ring formation regions. At the same time, a plurality ofdepressed portions 106 c for forming first buffer vias 131 (see FIG. 6)are formed in the portions of the first interlayer insulating film 106located in stress absorbing wall formation regions (the portions of thescribe region 103 which are adjacent to the chip regions 102). The sealvias are parts composing the seal rings and are formed by filling aconductive material in the trench-like depressed portions continuouslysurrounding the chip regions. Accordingly, each of the seal vias has alinear structure having a width substantially equal to the width of eachof the vias in the chip regions (see FIG. 3). The buffer vias are partscomposing the stress absorbing walls and are formed by filling aconductive material in the plurality of depressed portions discretelysurrounding the seal rings. Accordingly, the buffer vias are composed ofa plurality of linear components each having a width substantially equalto the width of each of the vias in the chip region.

Although the present embodiment has simultaneously formed thetrench-like depressed portions 106 b for forming the first seal vias 121and the depressed portions 106 c for forming the first buffer vias 131in forming the via holes 106 a in the portions of the first interlayerinsulating film 106 located in the chip regions 102, it will easily beappreciated that the via holes 106 a, the trench-like depressed portions106 b, and the depressed portions 106 c may be formed individually or,alternatively, any two of these depressed portions may be formedsimultaneously.

Next, as shown in FIG. 5, by using a lithographic technology and a dryetching technology, wire trenches 106 d for forming first wires 112 (seeFIG. 6) are formed in the portions of the first interlayer insulatingfilm 106 located in the chip regions 102 in such a manner as to connectto the via holes 106 a, while wire trenches 106 e for forming first sealwires 121 (see FIG. 6) are formed in the portions of the firstinterlayer insulating film 106 located in the seal ring formationregions in such a manner as to connect to the trench-like depressedportions 106 b. In addition, a wire trench 106 f for forming anaccessory wire 140, which serves as an alignment mark for lithography orthe like, may also be formed simultaneously in the portion of the firstinterlayer insulating film 106 located in the scribe region 103.

Next, as shown in FIG. 6, a conductive film made of, e.g., Cu is filledby using, e.g., an electric plating technology, in each of the via holes106 a, the trench-like depressed portions 106 b, the depressed portions106 c, and the wire trenches 106 d, 106 e, and 106 f. After that, theportion of the conductive film protruding from the depressed portions106 c and the wire trenches 106 d, 106 e, and 106 f (the portion of theconductive film which is located above the first interlayer insulatingfilm 106) is removed by, e.g., CMP (chemical mechanical polishing). As aresult, the first vias 111 connecting to the active layers 110 and thefirst wires 112 connecting to the first vias 111 (i.e., dual damascenewires composed of the first vias 111 and the first wires 112) are formedin the portions of the first interlayer insulating film 106 located inthe chip regions 102, while the first seal vias 121 connecting to theconductive layer 120 and the first seal wires 122 connecting to thefirst seal vias 121 are formed in the portions of the first interlayerinsulating film 106 located in the seal ring formation regions. On theother hand, the first buffer vias 131 are formed in the portions of thefirst interlayer insulating film 106 located in the stress absorbingwall formation regions, while the accessory wire 140 is formed in theportion of the first interlayer insulating film 106 located in thescribe region 103.

Then, as shown in FIG. 7, a second interlayer insulating film 107 isformed on the first interlayer insulating film 106 in the same manner asin the steps shown in FIGS. 4 to 6. Thereafter, second vias 113connecting to the first wires 112 and second wires 114 connecting to thesecond vias 113 (i.e., dual damascene wires composed of the second vias113 and the second wires 114) are formed in the portions of the secondinterlayer insulating film 107 located in the chip regions 102, whilesecond seal vias 123 connecting to the first seal wires 122 and secondseal wires 124 connecting to the second seal vias 123 are formed in theportions of the second interlayer insulating film 107 located in theseal ring formation regions. At the same time, second buffer vias 132connecting to the first buffer vias 131 are formed in the portions ofthe second interlayer insulating film 107 located in the stressabsorbing wall formation regions, while the accessory wire 140 is formedin the portion of the second interlayer insulating film 107 located inthe scribe region 103.

Subsequently, as shown in FIG. 7, a third interlayer insulating film 108is formed on the second interlayer insulating film 107 in the samemanner as in the steps shown in FIGS. 4 to 6. Then, third vias 115connecting to the second wires 114 and third wires 116 connecting to thethird vias 115 (i.e., dual damascene wires composed of the third vias115 and the third wires 116) are formed in the portions of the thirdinterlayer insulating film 108 located in the chip regions 102, whilethird seal vias 125 connecting to the second seal wires 124 and thirdseal wires 126 connecting to the third seal wires 125 are formed in theportions of the third interlayer insulating film 108 located in the sealring formation regions. At the same time, third buffer vias 133connecting to the second buffer vias 132 are formed in the portions ofthe third interlayer insulating film 108 located in the stress absorbingwall formation regions, while the accessory wire 140 is formed in theportion of the third interlayer insulating film 108 located in thescribe region 103.

The present embodiment has provided the dual damascene structurescomposed of the vias or the seal vias and the wires or the seal wires byusing Cu in each of the interlayer insulating films. However, it is alsopossible to provide the vias and the seal vias by using W (tungsten) inthe first-layer (lowermost-layer) interlayer insulating film, providethe wires and the seal wires (the lowermost-layer wires and seal wires)by using Cu in the second-layer interlayer insulating film, and providethe dual damascene structures composed of the vias or the seal vias andthe wires or the seal wires by using Cu in each of the third- andhigher-order-layer interlayer insulating films instead.

Then, as shown in FIG. 7, a passivation film 109 is deposited on thethird interlayer insulating film 108 serving as the uppermost wiringlayer to serve as a protective film therefor. Subsequently, openingscorresponding to the third wires 116 are formed locally in thepassivation film 109 by using a lithographic technology and a dryetching technology and then pad electrodes 117 connecting to the thirdwires 116 are formed in the openings, whereby the formation of theplurality of semiconductor devices in the wafer 101 is completed.

Thus, according to the present embodiment, the seal rings 104 composedof the seal vias 121, 123, and 125 and the seal wires 122, 124, and 126are formed simultaneously with the formation of the vias 111, 113, and115 and the wires 112, 114, and 116 in the chip regions 102. Inaddition, the stress absorbing walls 105 each having a multilayerstructure consisting of the buffer vias 131, 132, and 133 can be formedoutside the seal rings 104.

The wafer 101 thus formed with the semiconductor devices is diced alongthe scribe regions 103 and thereby separated into the individualsemiconductor devices (semiconductor chips). At this time, impact, astress, a crack resulting therefrom, or the like occurs first in thediced portion to propagate toward each of the chip regions 102. However,the impact, stress, crack, or the like is absorbed by the stressabsorbing walls 105. In other words, the further propagation of theimpact, stress, crack, or the like toward the chip regions 102 isblocked. This prevents damage to each of the seal rings 104 and allowseach of the seal rings to retain the function of preventing theingression of moisture, movable ions, or the like into the chip region102 from outside thereof, which is one of the intrinsic functions of theseal ring. As a result, it becomes possible to fabricate a semiconductordevice with high reliability.

According to the present embodiment, the individual components of eachof the stress absorbing walls 105 are arranged discretely andindependently of each other along the direction in which the seal ring104 extends. Therefore, even though any of the individual components isdamaged and destroyed by the crack or the like during wafer dicing,there is no such situation that the destruction of the stress absorbingwall 105 is enlarged along the direction in which the seal ring 104extends. That is, since the individual components of the stressabsorbing wall 105 are independent of each other, it becomes possible toprevent a component adjacent to the destroyed one from coming off as aresult of being pulled thereby. By reducing the size (specifically, thelength in the direction in which the seal ring 104 extends) of each ofthe components of the stress absorbing wall 105, even though any of thecomponents is destroyed under the influence of the impact, stress,crack, or the like during dicing, only the destroyed component comes offfrom one of the individual semiconductor devices into which the waferhas been separated (semiconductor chips after dicing).

In the case where the stress absorbing wall is continuously surroundingthe seal ring unlike in the present embodiment, the component the stressabsorbing wall that has been damaged by dicing and likely to come off isleft disadvantageously in the semiconductor chip after dicing by theother components of the stress absorbing wall connecting to the damagedcomponent. Consequently, when packaging is performed with respect to thesemiconductor chip, a defective product results from the contact betweenthe damaged component of the stress absorbing wall and a bonding wire.By contrast, the present embodiment can prevent the problem of thedefective product mentioned above since the damaged component of thestress absorbing wall comes off from the semiconductor chip after dicingwithout pulling the other components. A description will be given hereinbelow to the effect achieved by the present embodiment with reference tothe drawings.

FIG. 8 is a post-dicing cross-sectional view (cross-sectional view ofthe end portions of the semiconductor devices including seal ringportions positioned in the peripheral portions of the chip regions 102and, more specifically, of wiring structures in the chip regions 102 andthe structures of the seal rings 104) taken along the line A-A′ ofFIG. 1. FIG. 9 is a post-dicing plan view obtained by enlarging thevicinity of the line A-A′ of FIG. 1. FIGS. 8 and 9 are drawingscorresponding to FIGS. 2 and 3, respectively. Each of FIGS. 8 and 9shows the condition after dicing performed along the scribe region 103interposed between the pair of chip regions 102. FIG. 10 is across-sectional view of the post-dicing semiconductor device accordingto the present embodiment shown in FIG. 8, which has been mounted on alead frame.

As shown in FIG. 10, the post-dicing semiconductor device (i.e., thesubstrate 101) according to the present embodiment shown in FIG. 8 hasbeen mounted on a lead frame 150, while the lead frame 150 (the portionon which the semiconductor device has not been mounted) and the padelectrode 117 on the semiconductor device according to the presentembodiment have been connected to each other by using a bonding wire151. As shown in FIGS. 8 to 10, according to the present embodiment, thedamaged component of the stress absorbing wall 105 comes off from thechip after dicing (the post-dicing semiconductor device according to thepresent embodiment) without pulling the other components. Accordingly,it becomes possible to prevent a defective product resulting from thecontact between the damaged component of the stress absorbing wall 105and the bonding wire 151 when packaging is performed with respect to thesemiconductor chip.

By contrast, FIG. 11 is a cross-sectional view of the end portions ofpre-dicing semiconductor devices according to a comparative example,which comprise stress absorbing walls continuously surrounding sealrings. FIG. 12 is a plan view of the end portions. FIGS. 11 and 12 aredrawings corresponding to FIGS. 2 and 3, respectively. Each of FIGS. 11and 12 shows the respective end portions of a pair of chip regions witha scribe region interposed therebetween.

As shown in FIGS. 11 and 12, each of the pre-dicing semiconductordevices according to the comparative example is composed of a chipregion 52 and a scribe region 53. A seal ring 54 is formed in theportion of the chip region 52 which is adjacent to the boundary with thescribe region 53, while a stress absorbing wall 55 is formed outside theseal ring 54 (in the portion of the scribe region 53 which is adjacentto the chip region 52).

As shown in FIG. 11, active layers 60 composing elements such as atransistor are formed in the chip regions 52 of a wafer 51 (hereinafterreferred to as the substrate 51), while conductive layers 70 similarlyconstituted to the active layers 60 are formed in the peripheralportions (seal ring formation regions adjacent to the scribe region 53)of the chip regions 52 of the substrate 51.

As also shown in FIG. 11, a first interlayer insulating film 56 isformed on the substrate 51 and first vias 61 connecting to the activelayers 60 and first wires 62 connecting to the first vias 61 are formedin the portions of the first interlayer insulating film 56 located inthe chip regions 52, while first seal vias 71 connecting to theconductive layers 70 and first seal wires 72 connecting to the firstseal vias 71 are formed in the portions of the first interlayerinsulating film 56 located in the seal ring formation regions. On theother hand, first buffer vias 81 are formed in the portions of the firstinterlayer insulating film 56 located in the stress absorbing wallformation regions, while an accessory wire 90 is formed in the portionof the first interlayer insulating film 56 located in the scribe region53.

As also shown in FIG. 11, a second interlayer insulating film 57 isformed on the first interlayer insulating film 56 and second vias 63connecting to the first wires 62 and second wires 64 connecting to thesecond vias 63 are formed in the portions of the second interlayerinsulating film 57 located in the chip regions 52, while second sealvias 73 connecting to the first seal wires 72 and second seal wires 74connecting to the second seal vias 73 are formed in the portions of thesecond interlayer insulating film 57 located in the seal ring formationregions. On the other hand, second buffer vias 82 connecting to thefirst buffer vias 81 are formed in the portions of the second interlayerinsulating film 57 located in the stress absorbing wall formationregions, while the accessory wire 90 is formed in the portion of thesecond interlayer insulating film 57 located in the scribe region 53.

As also shown in FIG. 11, a third interlayer insulating film 58 isformed on the second interlayer insulating film 57 and third vias 65connecting to the second wires 64 and third wires 66 connecting to thethird vias 65 (i.e., dual damascene wires composed of the third vias 65and the third wires 66) are formed in the portions of the thirdinterlayer insulating film 58 located in the chip regions 52, whilethird seal vias 75 connecting to the second seal wires 74 and third sealwires 76 connecting to the third seal vias 75 are formed in the portionsof the third interlayer insulating film 58 located in the seal ringformation regions. On the other hand, third buffer vias 83 connecting tothe second buffer vias 82 are formed in the portions of the thirdinterlayer insulating film 58 located in the stress absorbing wallformation regions, while the accessory wire 90 is formed in the portionof the third interlayer insulating film 58 located in the scribe region53.

The comparative example has provided the dual damascene structurescomposed of the vias or the seal vias and the wires or the seal wires byusing Cu in each of the interlayer insulating films. However, it is alsopossible to provide the vias and the seal vias by using W in thefirst-layer (lowermost-layer) interlayer insulating film, provide thewires and the seal wires (the lowermost-layer wires and seal wires) byusing Cu in the second-layer interlayer insulating film, and provide thedual damascene structures composed of the vias or the seal vias and thewires or the seal wires by using Cu in each of the third- andhigher-order-layer interlayer insulating films instead.

As shown in FIG. 11, a passivation film 59 is further deposited on thethird interlayer insulating film 58 serving as the uppermost wiringlayer to serve as a protective film therefor. In addition, openingscorresponding to the third wires 66 are formed locally in thepassivation film 59 and pad electrodes 67 connecting to the third wires66 are formed in the openings.

As shown in FIG. 12, in the semiconductor device according to thecomparative example, the stress absorbing walls 55 are formed tocontinuously surround the seal rings 104, which is different from thepresent embodiment.

FIG. 13 is a cross-sectional view of the end portions of the post-dicingsemiconductor devices according to the comparative example. FIG. 14 is aplan view of the end portions. FIGS. 13 and 14 are drawingscorresponding to FIGS. 11 and 12, respectively. Each of FIGS. 13 and 14shows the respective end portions of the pair of chip regions with thescribe region interposed therebetween. FIG. 15 is a cross-sectional viewof the post-dicing semiconductor device according to the comparativeexample shown in FIG. 13, which has been mounted on a lead frame.

As shown in FIG. 15, the post-dicing semiconductor device (i.e., thesubstrate 51) according to the comparative example shown in FIG. 13 hasbeen mounted on a lead frame 40, while the lead frame 40 (the portion onwhich the semiconductor device has not been mounted) and the padelectrodes 67 on the semiconductor device according to the comparativeexample have been connected to each other by using a bonding wire 41. Asshown in FIGS. 13 to 15, in the comparative example, the component ofthe stress absorbing wall 55 that has been damaged by dicing and likelyto come off is left disadvantageously in the semiconductor chip afterdicing (the post-dicing semiconductor device according to thecomparative example) by the other components of the stress absorbingwall 55 connecting to the damaged component. Consequently, whenpackaging is performed with respect to the semiconductor chip, adefective product results from the contact between the damaged componentof the stress absorbing wall 55 and the bonding wire 41, as shown inFIG. 15.

Although the present embodiment has used the multilayer structureconsisting of the vias (the buffer vias 131, 132, and 133) as the stressabsorbing wall 105, it is also possible to use a multilayer structureconsisting of vias and wires, which is similar to that of the seal ring104, instead. Although the present embodiment has used the multilayerstructure consisting of the vias (seal vias 121, 123, and 125) and thewires (the seal wires 122, 124, and 126) as the seal ring 104, it isalso possible to use a multilayer structure consisting only of vias,which is similar to that of the stress absorbing wall 105. In the casewhere the multilayer structure consisting only of the vias is used aseach of the seal ring 104 and the stress absorbing wall 105, a region ina widthwise direction (direction perpendicular to the direction in whichthe seal ring 104 extends along the periphery of the chip region 102)occupied by the seal ring 104 and the stress absorbing wall 105 in thesemiconductor device can be reduced compared with the case where themultilayer structure consisting of the vias and the wires is used. Thisis effective in reducing the size of the semiconductor device.

In the present embodiment, at least one or more of the individualconductors (parts) that have been stacked in layers to compose the sealrings 104 are formed preferably in the step of forming the wires havingthe dual damascene structures. This allows the parts of the seal rings104 to penetrate at least one of the interlayer insulating films withoutleaving seams. That is, by forming the parts of the seal rings 104 inthe process of forming the dual damascene wires, the “seams” of each ofthe seal rings 104 can be reduced in the entire chip region 102 formedwith the seal ring, elements such as a transistor, a wiring layer, andthe like. As a result, it becomes possible to prevent the ingression ofimpact that has occurred during wafer dicing or moisture from theoutside into the chip region 102.

Although the present embodiment has formed the stress absorbing wall 105in the scribe region 103, it is not limited thereto. The same effect isobtainable irrespective of the position at which the stress absorbingwall 105 is formed provided that the stress absorbing wall 105 isinterposed between the diced portion of the wafer and the seal ring 104.Specifically, the stress absorbing wall 105 may also be provided outsidethe seal ring 104, e.g., in the portion of each of the chip regions 102which is adjacent to the boundary with the scribe region 103.

Although the present embodiment has provided the seal ring 104 in theportion of each of the chip regions 102 which is adjacent to theboundary with the scribe region 103, the seal ring 104 may also beprovided internally of the stress absorbing wall 105, e.g., in theportion of the scribe region 103 which remains as the end portion of thesemiconductor device (semiconductor chip) even after the dicing (i.e.,the portion of the scribe region 103 which is adjacent to the boundarywith the chip region 102).

Although the present embodiment has formed the wiring structure in thethree interlayer insulating films stacked in layers, the number of theinterlayer insulating films stacked in layers is not limited to 3. Itwill easily be appreciated that the number of the interlayer insulatingfilms stacked in layers may be smaller or larger than 3 depending on thechip structure.

Although the present embodiment has used Cu as a conductive material forcomposing each of the seal ring 104 and the stress absorbing wall 105,it is not limited thereto. It is also possible to use at least one of W,Al, and Cu to compose each of the seal ring 104 and the stress absorbingwall 105. This allows the seal ring 104 and the stress absorbing wall105 to be formed from the same material as composing the wires and thevias formed in the chip region 102 of the semiconductor device.

Embodiment 2

An electronic device according to a second embodiment of the presentinvention and a method for fabricating the same will be described withreference to the drawings.

FIG. 16 is a plan view showing a part of a wafer provided with anelectronic device (a semiconductor device having a seal ring singlysurrounding a chip region) according to the second embodiment.

As shown in FIG. 16, a plurality of chip regions 202, each of which isto serve as a semiconductor device, are arranged in a wafer 201 servingas a semiconductor substrate represented by, e.g., a silicon substrateor the like. Each of the chip regions 202 is provided with an ICcomposed of a plurality of elements and having a specified function. Theindividual chip regions 202 are defined by scribe regions 203 providedin a grid-like configuration.

Each one of the semiconductor devices (i.e., each one of thesemiconductor chips) is comprised herein of: a chip region 202 in whichan IC circuit composed of the plurality of elements and having thespecified function; a seal ring 204 provided in the peripheral portionof the chip region 202 to surround the chip region 202; and stressabsorbing walls 205 a and 205 b in a double structure according to thepresent invention which are provided outside the seal ring 204 todiscretely surround the seal ring 204. Thus, the semiconductor deviceaccording to the present embodiment has basically the same structure asthe semiconductor device according to the first embodiment except thatthe stress absorbing walls 205 are in the double structure.

In the present embodiment, the stress absorbing walls 205 in a double orhigher-order multiple structure, such as a triple or quadruplestructure, may also be provided depending on layout margin.

The wafer 201 thus formed with the plurality of semiconductor devices isdiced along the scribe regions 203 so that it is separated into theindividual semiconductor devices (semiconductor chips). At this time,since the stress absorbing walls 205 are formed in a double orhigher-order multiple structure to surround the chip region 202, eventhough one of the stress absorbing walls (specifically the outer stressabsorbing wall 205 b) is destroyed by impact, a stress, or the like thathas occurred during dicing or a crack resulting therefrom and theimpact, stress, or the like propagates inwardly, i.e., toward the innerportion the chip 202, the other stress absorbing wall (specifically theinner stress absorbing wall 205 a) located internally of the destroyedstress absorbing wall absorbs the impact, stress, or the like. Thissuccessfully prevents the impact, stress, crack, or the like fromreaching and thereby destroying the seal ring 204. Accordingly, itbecomes possible to prevent damage to the seal ring 204 and the chipregion 202 in the step of dividing the wafer 201 into the semiconductorchips and thereby prevent the degradation of the performance of thesemiconductor chip.

FIG. 17 is a cross-sectional view (cross-sectional view of the endportions of the semiconductor devices including seal ring portionspositioned in the peripheral portions of the chip regions 202 and, morespecifically, of wiring structures in the chip regions 202 and thestructures of the seal rings 204) taken along the line B-B′ of FIG. 16.FIG. 18 is a plan view obtained by enlarging the vicinity of the lineB-B′ of FIG. 16. Each of FIGS. 17 and 18 shows the respective endportions of the pair of chip regions 202 with the scribe region 203interposed therebetween.

As shown in FIGS. 17 and 18, each of the semiconductor devices prior todicing is composed of the chip region 202 and the scribe region 203. Theseal ring 204 is formed in the portion of the chip region 202 which isadjacent to the boundary with the scribe region 203, while the stressabsorbing walls 205 a and 205 b in the double structure are formedoutside the seal ring 204 (in the portions of the scribe region 203which are adjacent to the chip region 202).

A description will be given herein below to the method for fabricatingthe semiconductor device having the structure shown in FIGS. 17 and 18with reference to FIGS. 19, 20, 21, and 22.

First, as shown in FIG. 19, active layers 210 composing elements such asa transistor are formed in the chip regions 202 of the wafer 201(hereinafter referred to as the substrate 201), while conductive layers220 similarly constituted to the active layers 210 are formed in theperipheral portions (the regions to be formed with the seal rings whichare adjacent to the scribe region 203) of the chip regions 202 of thesubstrate 201.

Next, a first interlayer insulating film 206 is deposited on thesubstrate 201. Then, via holes 206 a for forming first vias 211 (seeFIG. 21) are formed in the portions of the first interlayer insulatingfilm 206 located in the chip regions 202 by using a lithographictechnology and a dry etching technology, while trench-like depressedportions 206 b for forming first seal vias (see FIG. 21) are formed inthe portions of the first interlayer insulating film 206 located in sealring formation regions. At the same time, a plurality of depressedportions 206 c for forming first buffer vias 231 a (see FIG. 21) and aplurality of depressed portions 206 d for forming first buffer vias 231b (see FIG. 21) are formed in the portions of the first interlayerinsulating film 206 located in stress absorbing wall formation regions(the portions of the scribe region 203 which are adjacent to the chipregions 202).

Although the present embodiment has simultaneously formed thetrench-like depressed portions 206 b for forming the first seal vias 221and the depressed portions 206 c and 206 d for forming the first buffervias 231 a and 231 b in forming the via holes 206 a in the portions ofthe first interlayer insulating film 206 located in the chip regions202, it will easily be appreciated that the via holes 206 a, thetrench-like depressed portions 206 b, and the depressed portions 206 cand 206 d may be formed individually or, alternatively, any two of thesedepressed portions may be formed simultaneously.

Next, as shown in FIG. 20, by using a lithographic technology and a dryetching technology, wire trenches 206 e for forming first wires 212 (seeFIG. 21) are formed in the portions of the first interlayer insulatingfilm 206 located in the chip regions 202 in such a manner as to connectto the via holes 206 a, while wire trenches 206 f for forming first sealwires 221 (see FIG. 21) are formed in the portions of the firstinterlayer insulating film 206 located in the seal ring formationregions in such a manner as to connect to the trench-like depressedportions 206 b. In addition, a wire trench 206 g for forming anaccessory wire 240, which serves as an alignment mark for lithography orthe like, may also be formed simultaneously in the portion of the firstinterlayer insulating film 206 located in the scribe region 203.

Next, as shown in FIG. 21, a conductive film made of, e.g., Cu is filledby using, e.g., an electric plating technology, in each of the via holes206 a, the trench-like depressed portions 206 b, the depressed portions206 c and 206 d, and the wire trenches 206 e, 206 f, and 206 g. Afterthat, the portion of the conductive film protruding from the depressedportions 206 c and 206 d and the wire trenches 206 e, 206 f, and 206 g(the portion of the conductive film which is located above the firstinterlayer insulating film 206) is removed by, e.g., CMP (chemicalmechanical polishing). As a result, the first vias 211 connecting to theactive layer 210 and the first wires 212 connecting to the first vias211 (i.e., dual damascene wires composed of the first vias 211 and thefirst wires 212) are formed in the portions of the first interlayerinsulating film 206 located in the chip regions 202, while the firstseal vias 221 connecting to the conductive layer 220 and the first sealwires 222 connecting to the first seal vias 221 are formed in theportions of the first interlayer insulating film 206 located in the sealring formation regions. On the other hand, the first buffer vias 231 aand 231 b are formed in the portions of the first interlayer insulatingfilm 206 located in the stress absorbing wall formation regions, whilethe accessory wire 240 is formed in the portion of the first interlayerinsulating film 206 located in the scribe region 203.

Then, as shown in FIG. 22, a second interlayer insulating film 207 isformed on the first interlayer insulating film 206 in the same manner asin the steps shown in FIGS. 19 to 21. Thereafter, second vias 213connecting to the first wires 212 and second wires 214 connecting to thesecond vias 213 (i.e., dual damascene wires composed of the second vias213 and the second wires 214) are formed in the portions of the secondinterlayer insulating film 207 located in the chip regions 202, whilesecond seal vias 223 connecting to the first seal wires 222 and secondseal wires 224 connecting to the second seal vias 223 are formed in theportions of the second interlayer insulating film 207 located in theseal ring formation regions. At the same time, second buffer vias 232 aand 232 b connecting to the first buffer vias 231 a and 231 b are formedin the portions of the second interlayer insulating film 207 located inthe stress absorbing wall formation regions, while the accessory wire240 is formed in the portion of the second interlayer insulating film207 located in the scribe region 203.

Subsequently, as shown in FIG. 22, a third interlayer insulating film208 is formed on the second interlayer insulating film 207 in the samemanner as in the steps shown in FIGS. 19 to 21. Then, third vias 215connecting to the second wires 214 and third wires 216 connecting to thethird vias 215 (i.e., dual damascene wires composed of the third vias215 and the third wires 216) are formed in the portions of the thirdinterlayer insulating film 208 located in the chip regions 202, whilethird seal vias 225 connecting to the second seal wires 224 and thirdseal wires 226 connecting to the third seal wires 225 are formed in theportions of the third interlayer insulating film 208 located in the sealring formation regions. At the same time, third buffer vias 233 a and233 b connecting to the second buffer vias 232 a and 232 b are formed inthe portions of the third interlayer insulating film 208 located in thestress absorbing wall formation regions, while the accessory wire 240 isformed in the portion of the third interlayer insulating film 208located in the scribe region 203.

The present embodiment has provided the dual damascene structurescomposed of the vias or the seal vias and the wires or the seal wires byusing Cu in each of the interlayer insulating films. However, it is alsopossible to provide the vias and the seal vias by using W in thefirst-layer (lowermost-layer) interlayer insulating film, provide thewires and the seal wires (the lowermost-layer wires and seal wires) byusing Cu in the second-layer interlayer insulating film, and provide thedual damascene structures composed of the vias or the seal vias and thewires or the seal wires by using Cu in each of the third- andhigher-order-layer interlayer insulating films instead.

Then, as shown in FIG. 22, a passivation film 209 is deposited on thethird interlayer insulating film 208 serving as the uppermost wiringlayer to serve as a protective film therefor. Subsequently, openingscorresponding to the third wires 216 are formed locally in thepassivation film 209 by using a lithographic technology and a dryetching technology and then pad electrodes 217 connecting to the thirdwires 216 are formed in the openings, whereby the formation of theplurality of semiconductor devices in the wafer 201 is completed.

In short, the method for fabricating the semiconductor device accordingto the present embodiment is the same as the method for fabricating thesemiconductor device according to the first embodiment except that thestress absorbing walls 205 are formed in the double structure, i.e., thetwo multilayer structures consisting of the buffer vias are formed.

Thus, according to the present embodiment, the seal rings 204 composedof the seal vias 221, 223, and 225 and the seal wires 222, 224, and 226are formed simultaneously with the formation of the vias 211, 213, and215 and the wires 212, 214, and 216 in the chip regions 202. Inaddition, the stress absorbing walls 205 a each having a multilayerstructure consisting of the buffer vias 231 a, 232 a, and 233 a and thestress absorbing walls 205 b each having a multilayer structureconsisting of the buffer vias 231 b, 232 b, and 233 b, i.e., the stressabsorbing walls 205 each having the double structure can be formedoutside the seal rings 204.

The wafer 201 thus formed with the semiconductor devices in accordancewith the method described above is diced along the scribe regions 203and thereby separated into the individual semiconductor devices(semiconductor chips). At this time, impact, a stress, a crack resultingtherefrom, or the like occurs first in the diced portion to propagatetoward each of the chip regions 202. At this time, even though the outerstress absorbing wall 205 b is destroyed by the impact, stress, crack,or the like and the impact or the like propagates toward the innerportion of the chip region 202, the impact, stress, crack, or the likeis absorbed by the stress absorbing wall 205 a located internally of thedestroyed stress absorbing wall 205 b so that the further propagation ofthe impact or the like toward the inner portion of the chip region 202is prevented successfully. This successfully prevents damage to each ofthe seal rings 204 and allows the seal ring 204 to retain the functionof preventing the ingression of moisture, movable ions, or the like intothe chip region 202 from outside thereof, which is one of the intrinsicfunctions of the seal ring 204. As a result, it becomes possible tofabricate a semiconductor device with high reliability.

According to the present embodiment, the individual components of eachof the stress absorbing walls 205 a and 205 b are arranged discretelyand independently of each other along the direction in which the sealring 204 extends. Therefore, even though any of the individualcomponents is damaged and destroyed by the crack or the like duringwafer dicing, there is no such situation that the destruction of thestress absorbing wall 205 a or 205 b is enlarged along the direction inwhich the seal ring 204 extends. That is, since the individualcomponents of the stress absorbing walls 205 a and 205 b are independentof each other, it becomes possible to prevent a component adjacent tothe destroyed one from coming off as a result of being pulled thereby.By reducing the size (specifically, the length in the direction in whichthe seal ring 204 extends) of each of the components of the stressabsorbing walls 205 a and 205 b, even though any of the components isdestroyed under the influence of the impact, stress, crack, or the likeduring dicing, only the destroyed component comes off from one of theindividual semiconductor devices into which the wafer has been separated(semiconductor chips after dicing). That is, since the damaged componentof the stress absorbing wall comes off from the semiconductor chip afterdicing without pulling the components, the occurrence of a defectiveproduct resulting from the contact between the damaged component of thestress absorbing wall and a bonding wire can be prevented when packagingis performed with respect to the semiconductor chip.

Although the present embodiment has used the multilayer structuresconsisting of the vias (the buffer vias 231 a, 231 b, 232 a, 232 b, 233a, and 233 b) as the stress absorbing walls 205 a and 205 b, it is alsopossible to use multilayer structures each consisting of vias and wires,which is similar to the multilayer structure of the seal ring 204,instead. Although the present embodiment has used the multilayerstructure consisting of the vias (seal vias 221, 223, and 225) and thewires (the seal wires 222, 224, and 226) as the seal ring 204, it isalso possible to use a multilayer structure consisting only of vias,which is similar to that of each of the stress absorbing walls 205 a and205 b. In the case where the multilayer structure consisting only of thevias is used as each of the seal ring 204 and the stress absorbing walls205 a and 205 b, a region in a widthwise direction (directionperpendicular to the direction in which the seal ring 204 extends alongthe periphery of the chip region 202) occupied by the seal ring 204 andthe stress absorbing walls 205 a and 205 b in the semiconductor devicecan be reduced compared with the case where the multilayer structureconsisting of the vias and the wires is used. This is effective inreducing the size of the semiconductor device.

In the present embodiment, at least one or more of the individualconductors (parts) that have been stacked in layers to compose each ofthe seal rings 204 are formed preferably in the step of forming thewires having the dual damascene structures. This allows the parts of theseal rings 204 to penetrate through at least one of the interlayerinsulating films without leaving seams. That is, by forming the parts ofthe seal rings 204 in the process of forming the dual damascene wires,the “seams” of each of the seal rings 204 can be reduced in the entirechip region 202 formed with the seal ring, elements such as atransistor, a wiring layer, and the like. As a result, it becomespossible to prevent the ingression of impact that has occurred duringwafer dicing or moisture from the outside into the chip region 202.

Although the present embodiment has formed the stress absorbing walls205 a and 205 b in the scribe region 203, it is not limited thereto. Thesame effect is obtainable irrespective of the positions at which thestress absorbing walls 205 a and 205 b are formed provided that thestress absorbing walls 205 a and 205 b are interposed between the dicedportion of the wafer and the seal ring 204. Specifically, the stressabsorbing walls 205 a and 205 b may also be provided outside the sealring 204, e.g., in the portions of each of the chip regions 202 whichare adjacent to the boundary with the scribe region 203.

Although the present embodiment has provided the seal ring 204 in theportion of each of the chip regions 202 which is adjacent to theboundary with the scribe region 203, the seal ring 204 may also beprovided internally of the stress absorbing walls 205 a and 205 b, e.g.,in the portion of the scribe region 203 which remains as the end portionof the semiconductor device (semiconductor chip) even after the dicing(i.e., the portion of the scribe region 203 which is adjacent to theboundary with the chip region 202).

Although the present embodiment has formed the wiring structure in thethree interlayer insulating films stacked in layers, the number of theinterlayer insulating films stacked in layers is not limited to 3. Itwill easily be appreciated that the number of the interlayer insulatingfilms stacked in layers may be smaller or larger than 3 depending on thechip structure.

Although the present embodiment has used Cu as a conductive material forconstituting each of the seal ring 204 and the stress absorbing walls205 a and 205 b, it is not limited thereto. It is also possible to useat least one of W, Al, and Cu to compose each of the seal ring 204 andthe stress absorbing walls 205 a and 205 b. This allows the seal ring204 and the stress absorbing walls 205 a and 205 b to be formed from thesame material as composing the wires and the vias formed in the chipregion 202 of the semiconductor device.

Embodiment 3

An electronic device according to a third embodiment of the presentinvention and a method for fabricating the same will be described withreference to the drawings.

FIG. 23 is a plan view showing a part of a wafer provided with anelectronic device (a semiconductor device having a seal ring singlysurrounding a chip region) according to the third embodiment.

As shown in FIG. 23, a plurality of chip regions 302, each of which isto serve as a semiconductor device, are arranged in a wafer 301 servingas a semiconductor substrate represented by, e.g., a silicon substrateor the like. Each of the chip regions 302 is provided with an ICcomposed of a plurality of elements and having a specified function. Theindividual chip regions 302 are defined by scribe regions 303 providedin a grid-like configuration.

Each one of the semiconductor devices (i.e., each one of thesemiconductor chips) is comprised herein of: a chip region 302 in whichan IC circuit composed of the plurality of elements and having thespecified function; a seal ring 304 provided in the peripheral portionof the chip region 302 to surround the chip region 302; and stressabsorbing walls 305 a and 305 b in a double structure according to thepresent invention which are provided outside the seal ring 304 todiscretely surround the seal ring 304. Thus, in the same manner as inthe second embodiment, the semiconductor device according to the presentembodiment has basically the same structure as the semiconductor deviceaccording to the first embodiment except that the stress absorbing walls305 are in the double structure. In contrast to the semiconductor deviceaccording to the second embodiment in which the respective gap portionsof the stress absorbing walls 205 a and 205 b in the double structureare aligned in rows, the respective gap portions of the stress absorbingwalls 305 a and 305 b in the double structure are not aligned in rows inthe semiconductor device according to the third embodiment.

In the present embodiment, the stress absorbing walls 305 in a double orhigher-order multiple structure, such as a triple or quadruplestructure, may also be provided depending on layout margin.

The wafer 301 thus formed with the plurality of semiconductor devices isdiced along the scribe regions 303 so that it is separated into theindividual semiconductor devices (semiconductor chips). At this time,since the stress absorbing walls 305 are formed in a double orhigher-order multiple structure to surround the chip region 302, eventhough one of the stress absorbing walls (specifically the outer stressabsorbing wall 305 b) is destroyed by impact, a stress, or the like thathas occurred during dicing or a crack resulting therefrom and theimpact, stress, or the like propagates inwardly, i.e., toward the innerportion of the chip 302, the other stress absorbing wall (specificallythe inner stress absorbing wall 305 a) located internally of thedestroyed stress absorbing wall absorbs the impact, stress, or the like.This successfully prevents the impact, stress, crack, or the like fromreaching and thereby destroying the seal ring 304.

In addition, the stress absorbing walls 305 a and 305 b in the doublestructure are formed such that the respective gap portions thereof arenot aligned in rows. When the seal ring 304 and the chip region 302 areviewed from the diced portion of the wafer, therefore, the respectiveportions composing the stress absorbing walls 305 a and 305 b arearranged with no space therebetween to form a whole entity. This allowsthe inner stress absorbing wall 305 a to reliably absorb the impact,stress, crack, or the like that has occurred during dicing andpropagated toward the chip region 302 through the discrete portions ofthe outer stress absorbing wall 305 b. As a result, it becomes possibleto prevent damage to the seal ring 304 and the chip region 302 in thestep of dividing the wafer 301 into semiconductor chips and therebyprevent the degradation of the performance of each of the semiconductorchips.

FIG. 24 is a cross-sectional view (cross-sectional view of the endportions of the semiconductor devices including seal ring portionspositioned in the peripheral portions of the chip regions 302 and, morespecifically, of wiring structures in the chip regions 302 and thestructures of the seal rings 304) taken along the line C-C′ of FIG. 23.FIG. 25 is a plan view obtained by enlarging the vicinity of the lineC-C′ of FIG. 23. Each of FIGS. 24 and 25 shows the respective endportions of the pair of chip regions 302 with the scribe region 303interposed therebetween. FIG. 24 shows a cross-sectional structure at aposition where the respective portions composing the stress absorbingwalls 305 a and 305 b in the double structure are partly alignedhorizontally. Since the respective gap portions of the stress absorbingwalls 305 a and 305 b in the double structure are not aligned in rows inthe present embodiment, at least one of the portions composing thestress absorbing wall 305 a and the portions composing the stressabsorbing wall 305 b is observed in a cross-sectional structure taken atany position in the stress absorbing wall formation regions.

As shown in FIGS. 24 and 25, each of the semiconductor devices prior todicing is composed of the chip region 302 and the scribe region 303. Theseal ring 304 is formed in the portion of the chip region 302 which isadjacent to the boundary with the scribe region 303, while stressabsorbing walls 305 a and 305 b in the double structure are formedoutside the seal ring 304 (in the portions of the scribe region 303which are adjacent to the chip regions 302).

As shown in FIG. 24, active layers 310 composing elements such as atransistor are formed in the chip regions 302 of a wafer 301(hereinafter referred to as the substrate 301), while conductive layers320 similarly constituted to the active layers 310 are formed in theperipheral portions (seal ring formation regions adjacent to the scriberegion 303) of the chip regions 302 of the substrate 301. A firstinterlayer insulating film 306 is formed on the substrate 301 and firstvias 331 connecting to the active layers 310 and first wires 312connecting to the first vias 331 (i.e., dual damascene wires composed ofthe first vias 311 and the first wires 312) are formed in the portionsof the first interlayer insulating film 306 located in the chip regions302, while first seal vias 321 connecting to the conductive layers 420and first seal wires 322 connecting to the first seal vias 321 areformed in the portions of the first interlayer insulating film 306located in the seal ring formation regions. On the other hand, firstbuffer vias 331 a and 331 b are formed in the portions of the firstinterlayer insulating film 306 located in the stress absorbing wallformation regions, while an accessory wire 340 is formed in the portionof the first interlayer insulating film 306 located in the scribe region303.

As also shown in FIG. 24, a second interlayer insulating film 307 isformed on the first interlayer insulating film 306 and second vias 313connecting to the first wires 312 and second wires 314 connecting to thesecond vias 313 (i.e., dual damascene wires composed of the second vias313 and the second wires 314) are formed in the portions of the secondinterlayer insulating film 307 located in the chip regions 302, whilesecond seal vias 323 connecting to the first seal wires 322 and secondseal wires 324 connecting to the second seal vias 323 are formed in theportions of the second interlayer insulating film 307 located in theseal ring formation regions. On the other hand, second buffer vias 332 aand 332 b connecting to the respective first buffer vias 331 a and 331 bare formed in the portions of the second interlayer insulating film 307located in the stress absorbing wall formation regions, while theaccessory wire 340 is formed in the portion of the second interlayerinsulating film 307 located in the scribe region 303.

As also shown in FIG. 24, a third interlayer insulating film 308 isformed on the second interlayer insulating film 307 and third vias 315connecting to the second wires 314 and third wires 316 connecting to thethird vias 315 (i.e., dual damascene wires composed of the third vias315 and the third wires 316) are formed in the portions of the thirdinterlayer insulating film 308 located in the chip regions 302, whilethird seal vias 325 connecting to the second seal wires 324 and thirdseal wires 326 connecting to the third seal vias 325 are formed in theportions of the third interlayer insulating film 308 located in the sealring formation regions. On the other hand, third buffer vias 333 a and333 b connecting to the second buffer vias 332 a and 332 b are formed inthe portions of the third interlayer insulating film 308 located in thestress absorbing wall formation regions, while the accessory wire 340 isformed in the portion of the third interlayer insulating film 308located in the scribe region 303.

The present embodiment has provided the dual damascene structurescomposed of the vias or the seal vias and the wires or the seal wires byusing Cu in each of the interlayer insulating films. However, it is alsopossible to provide the vias and the seal vias by using W in thefirst-layer (lowermost-layer) interlayer insulating film, provide thewires and the seal wires (the lowermost-layer wires and seal wires) byusing Cu in the second-layer interlayer insulating film, and provide thedual damascene structures composed of the vias or the seal vias and thewires or the seal wires by using Cu in each of the third- andhigher-order-layer interlayer insulating films instead.

As shown in FIG. 24, a passivation film 309 is further deposited on thethird interlayer insulating film 308 serving as the uppermost wiringlayer to serve as a protective film therefor. In addition, openingscorresponding to the third wires 316 are formed locally in thepassivation film 309 and pad electrodes 317 connecting to the thirdwires 316 are formed in the openings.

The method for fabricating the semiconductor device having the structureshown in FIGS. 23 to 25 according to the present embodiment is basicallythe same as the method for fabricating the semiconductor deviceaccording to the second embodiment shown in FIGS. 19 to 22, except forthe layout of a mask pattern for forming the stress absorbing walls inthe double structure in a photo mask in use.

Thus, according to the present embodiment, the seal rings 304 composedof the seal vias 321, 323, and 325 and the seal wires 322, 324, and 326are formed simultaneously with the formation of the vias 311, 313, and315 and the wires 312, 314, and 316 in the chip regions 302. Inaddition, the stress absorbing walls 305 a each having a multilayerstructure consisting of the buffer vias 331 a, 332 a, and 333 a and thestress absorbing walls 305 b each having a multilayer structureconsisting of the buffer vias 331 b, 332 b, and 333 b, i.e., the stressabsorbing walls 305 each having the double structure can be formedoutside the seal rings 304.

The wafer 301 thus formed with the semiconductor devices in accordancewith the method described above is diced along the scribe regions 303and thereby separated into the individual semiconductor devices(semiconductor chips). At this time, impact, a stress, a crack resultingtherefrom, or the like occurs first in the diced portion to propagatetoward each of the chip regions 302. At this time, even though the outerstress absorbing wall 305 b is destroyed by the impact, stress, crack,or the like and the impact or the like propagates toward the innerportion of the chip region 302, the impact, stress, crack, or the likeis absorbed by the stress absorbing wall 305 a located internally of thedestroyed stress absorbing wall 305 b so that the further propagation ofthe impact or the like toward the inner portion of the chip region 302is prevented successfully. This successfully prevents damage to each ofthe seal rings 304 and allows the seal ring 304 to retain the functionof preventing the ingression of moisture, movable ions, or the like intothe chip region 302 from outside thereof, which is one of the intrinsicfunctions of the seal ring 304. As a result, it becomes possible tofabricate a semiconductor device with high reliability.

According to the present embodiment, the stress absorbing walls 305 aand 305 b in the double structure are formed such that the respectivegap portions thereof are not aligned in rows. When the seal ring 304 andthe chip region 302 are viewed from the diced portion of the wafer,therefore, the respective portions composing the stress absorbing walls305 a and 305 b are arranged with no space therebetween to form a wholeentity. This allows the inner stress absorbing wall 305 a to reliablyabsorb the impact, stress, crack, or the like that has occurred duringdicing and propagated toward the chip region 302 through the discreteportions of the outer stress absorbing wall 305 b. As a result, damageto the seal ring 304 can be prevented and the seal ring 304 is allowedto retain the function of preventing the ingression of moisture, movableions, or the like into the chip region 302 from outside thereof, whichis one of the intrinsic functions of the seal ring 304. Accordingly, itbecomes possible to provide a semiconductor device with highreliability.

Although the present embodiment has used the multilayer structuresconsisting of the vias (the buffer vias 331 a, 331 b, 332 a, 332 b, 333a, and 333 b) as the stress absorbing walls 305 a and 305 b, it is alsopossible to use multilayer structures each consisting of vias and wires,which is similar to the multiple structure of the seal ring 304,instead. Although the present embodiment has used the multilayerstructure consisting of the vias (seal vias 321, 323, and 325) and thewires (the seal wires 322, 324, and 326) as the seal ring 304, it isalso possible to use a multilayer structure consisting only of vias,which is similar to that of each of the stress absorbing walls 305 a and305 b. In the case where the multilayer structure consisting only of thevias is used as each of the seal ring 304 and the stress absorbing walls305 a and 305 b, a region in a widthwise direction (directionperpendicular to the direction in which the seal ring 304 extends alongthe periphery of the chip region 302) occupied by the seal ring 304 andthe stress absorbing walls 305 a and 305 b in the semiconductor devicecan be reduced compared with the case where the multilayer structureconsisting of the vias and the wires is used. This is effective inreducing the size of the semiconductor device.

In the present embodiment, at least one or more of the individualconductors (parts) that have been stacked in layers to compose each ofthe seal rings 304 are formed preferably in the step of forming thewires having the dual damascene structures. This allows the parts of theseal rings 304 to penetrate through at least one of the interlayerinsulating films without leaving seams. That is, by forming the parts ofthe seal rings 304 in the process of forming the dual damascene wires,the “seams” of each of the seal rings 304 can be reduced in the entirechip region 302 formed with the seal ring, elements such as atransistor, a wiring layer, and the like. As a result, it becomespossible to prevent the ingression of impact that has occurred duringwafer dicing or moisture from the outside into the chip region 302.

Although the present embodiment has formed the stress absorbing walls305 a and 305 b in the scribe region 303, it is not limited thereto. Thesame effect is obtainable irrespective of the positions at which thestress absorbing walls 305 a and 305 b are formed provided that thestress absorbing walls 305 a and 305 b are interposed between the dicedportion of the wafer and the seal ring 304. Specifically, the stressabsorbing walls 305 a and 305 b may also be provided outside the sealring 304, e.g., in the portions of each of the chip regions 302 whichare adjacent to the boundary with the scribe region 303.

Although the present embodiment has provided the seal ring 304 in theportion of each of the chip regions 302 which is adjacent to theboundary with the scribe region 303, the seal ring 304 may also beprovided internally of the stress absorbing walls 305 a and 305 b, e.g.,in the portion of the scribe region 303 which remains as the end portionof the semiconductor device (semiconductor chip) even after the dicing(i.e., the portion of the scribe region 303 which is adjacent to theboundary with the chip region 302).

Although the present embodiment has formed the wiring structure in thethree interlayer insulating films stacked in layers, the number of theinterlayer insulating films stacked in layers is not limited to 3. Itwill easily be appreciated that the number of the interlayer insulatingfilms stacked in layers may be smaller or larger than 3 depending on thechip structure.

Although the present embodiment has used Cu as a conductive material forconstituting each of the seal ring 304 and the stress absorbing walls305 a and 305 b, it is not limited thereto. It is also possible to useat least one of W, Al, and Cu to compose each of the seal ring 304 andthe stress absorbing walls 305 a and 305 b. This allows the seal ring304 and the stress absorbing walls 305 a and 305 b to be formed from thesame material as composing the wires and the vias formed in the chipregion 302 of the semiconductor device.

Embodiment 4

An electronic device according to a fourth embodiment of the presentinvention and a method for fabricating the same will be described withreference to the drawings.

FIG. 26 is a plan view showing a part of a wafer provided with anelectronic device (a semiconductor device having a seal ring singlysurrounding a chip region) according to the fourth embodiment.

As shown in FIG. 26, a plurality of chip regions 402, each of which isto serve as a semiconductor device, are arranged in a wafer 401 servingas a semiconductor substrate represented by, e.g., a silicon substrateor the like. Each of the chip regions 402 is provided with an ICcomposed of a plurality of elements and having a specified function. Theindividual chip regions 402 are defined by scribe regions 403 providedin a grid-like configuration.

Each one of the semiconductor devices (i.e., each one of thesemiconductor chips) is comprised herein of: a chip region 402 in whichan IC circuit composed of the plurality of elements and having thespecified function; a seal ring 404 provided in the peripheral portionof the chip region 402 to surround the chip region 402; and stressabsorbing walls 405 a and 405 b in a double structure according to thepresent invention which are provided outside the seal ring 404 todiscretely surround the seal ring 404. Thus, in the same manner as inthe second or third embodiment, the semiconductor device according tothe present embodiment has basically the same structure as thesemiconductor device according to the first embodiment except that thestress absorbing walls 205 are in the double structure. A characteristicfeature peculiar to the semiconductor device according to the presentembodiment is that, in the stress absorbing walls 405 a and 405 b in thedouble structure, each of the components of the outer stress absorbingwall 405 b is shorter in length along a direction in which the seal ring404 extends than each of the components of the inner stress absorbingwall 405 a.

In the present embodiment, the stress absorbing walls 405 in a double orhigher-order multiple structure, such as a triple or quadruplestructure, may also be provided depending on layout margin. In thiscase, each of the components of the stress absorbing wall 405 in adouble or higher-order multiple structure which is formed at a positionmost distant from the seal ring 404 is shorter in length alongdirections in which the seal rings 404 extend than each of thecomponents of the other stress absorbing wall or walls 405.

A wafer 401 thus formed with the plurality of semiconductor devices isdiced along the scribe regions 403 so that it is separated into theindividual semiconductor devices (semiconductor chips). At this time,since the stress absorbing walls 405 are formed in a double orhigher-order multiple structure to surround the chip region 402, eventhough one of the stress absorbing walls (specifically the outer stressabsorbing wall 405 b) is destroyed by impact, a stress, or the like thathas occurred during dicing or a crack resulting therefrom and theimpact, stress, or the like propagates inwardly, e.g., toward the innerportion of the chip 402, the other stress absorbing wall (specificallythe inner stress absorbing wall 405 a) located internally of thedestroyed stress absorbing wall absorbs the impact, stress, or the like.This successfully prevents the impact, stress, crack, or the like fromreaching and thereby destroying the seal ring 404.

In addition, since each of the components of the stress absorbing wall405 b at a position closest to the diced portion of the wafer, i.e., ofthe stress absorbing wall 405 b formed at a position most distant fromthe seal ring 404 is smaller in length, a crack, impact, or the likethat has occurred during dicing can be finely distributed and absorbed.As a result, it becomes possible to prevent damage to the seal ring 404and the chip region 402 when the wafer 401 is divided into individualsemiconductor chips and thereby prevent the degradation of theperformance of each of the semiconductor chips. Since each of thecomponents of the stress absorbing wall 405 b is smaller in size, eventhough the component receives a crack, impact, or the like during dicingand is destroyed thereby, the component easily comes off from thesemiconductor device (one of the individual semiconductor chips intowhich the wafer has been separated). This prevents a situation where thedestroyed component is left protruding from the end portion of thesemiconductor chip after dicing and thereby eliminates a defectiveproduct resulting from the contact between the residue of the stressabsorbing wall 405 b and a bonding wire when packaging is performed withrespect to the semiconductor chip.

FIG. 27 is a cross-sectional view (cross-sectional view of the endportions of the semiconductor devices including seal ring portionspositioned in the peripheral portion of the chip regions 402 and, morespecifically, of wiring structures in the chip regions 402 and thestructures of the seal rings 404) taken along the line D-D′ of FIG. 26.FIG. 28 is a plan view obtained by enlarging the vicinity of the lineD-D′ of FIG. 26. Each of FIGS. 27 and 28 shows the respective endportions of the pair of chip regions 402 with the scribe region 403interposed therebetween. FIG. 27 shows a cross-sectional structure at aposition where the respective portions composing the stress absorbingwalls 305 a and 305 b in the double structure are partly alignedhorizontally.

As shown in FIGS. 27 and 28, each of the semiconductor devices prior todicing is composed of the chip region 402 and the scribe region 403. Theseal ring 404 is formed in the portion of the chip region 402 which isadjacent to the boundary with the scribe region 303, while stressabsorbing walls 405 a and 405 b in the double structure are formedoutside the seal ring 404 (in the portions of the scribe region 403which are adjacent to the chip regions 402).

As shown in FIG. 27, active layers 410 composing elements such as atransistor are formed in the chip regions 402 of a wafer 401(hereinafter referred to as the substrate 301), while conductive layers420 similarly constituted to the active layers 410 are formed in theperipheral portions of the chip regions 402 of the substrate 401. Afirst interlayer insulating film 406 is formed on the substrate 301 andfirst vias 431 connecting to the active layers 410 and first wires 412connecting to the first vias 431 (i.e., dual damascene wires composed ofthe first vias 411 and the first wires 412) are formed in the portionsof the first interlayer insulating film 406 located in the chip regions402, while first seal vias 421 connecting to the conductive layer 420and first seal wires 422 connecting to the first seal vias 421 areformed in the portions of the first interlayer insulating film 406located in the seal ring formation regions. On the other hand, firstbuffer vias 431 a and 431 b are formed in the portions of the firstinterlayer insulating film 406 located in the stress absorbing wallformation regions, while an accessory wire 440 is formed in the portionof the first interlayer insulating film 406 located in the scribe region403.

As also shown in FIG. 27, a second interlayer insulating film 407 isformed on the first interlayer insulating film 406 and second vias 413connecting to the first wires 412 and second wires 414 connecting to thesecond vias 413 (i.e., dual damascene wires composed of the second vias413 and the second wires 414) are formed in the portions of the secondinterlayer insulating film 407 located in the chip regions 402, whilesecond seal vias 423 connecting to the first seal wires 422 and secondseal wires 424 connecting to the second seal vias 423 are formed in theportions of the second interlayer insulating film 407 located in theseal ring formation regions. On the other hand, second buffer vias 432 aand 432 b connecting to the respective first buffer vias 431 a and 431 bare formed in the portions of the second interlayer insulating film 407located in the stress absorbing wall formation regions, while theaccessory wire 440 is formed in the portion of the second interlayerinsulating film 407 located in the scribe region 403.

As also shown in FIG. 27, a third interlayer insulating film 408 isformed on the second interlayer insulating film 407 and third vias 415connecting to the second wires 314 and third wires 416 connecting to thethird vias 415 (i.e., dual damascene wires composed of the third vias415 and the third wires 416) are formed in the portions of the thirdinterlayer insulating film 408 located in the chip regions 402, whilethird seal vias 425 connecting to the second seal wires 424 and thirdseal wires 426 connecting to the third seal vias 425 are formed in theportions of the third interlayer insulating film 408 located in the sealring formation regions. On the other hand, third buffer vias 433 a and433 b connecting to the second buffer vias 432 a and 432 b are formed inthe portions of the third interlayer insulating film 408 located in thestress absorbing wall formation regions, while the accessory wire 440 isformed in the portion of the third interlayer insulating film 408located in the scribe region 403.

The present embodiment has provided the dual damascene structurescomposed of the vias or the seal vias and the wires or the seal wires byusing Cu in each of the interlayer insulating films. However, it is alsopossible to provide the vias and the seal vias by using W in thefirst-layer (lowermost-layer) interlayer insulating film, provide thewires and the seal wires (the lowermost-layer wires and seal wires) byusing Cu in the second-layer interlayer insulating film, and provide thedual damascene structures composed of the vias or the seal vias and thewires or the seal wires by using Cu in each of the third- andhigher-order-layer interlayer insulating films instead.

As shown in FIG. 27, a passivation film 409 is further deposited on thethird interlayer insulating film 408 serving as the uppermost wiringlayer to serve as a protective film therefor. In addition, openingscorresponding to the third wires 416 are formed locally in thepassivation film 409 and pad electrodes 417 connecting to the thirdwires 416 are formed in the openings.

The method for fabricating the semiconductor device having the structureshown in FIGS. 26 to 28 according to the present embodiment is basicallythe same as the method for fabricating the semiconductor deviceaccording to the second embodiment shown in FIGS. 19 to 22, except forthe layout of a mask pattern for forming the stress absorbing walls inthe double structure in a photo mask in use.

Thus, according to the present embodiment, the seal rings 404 composedof the seal vias 421, 423, and 425 and the seal wires 422, 424, and 426are formed simultaneously with the formation of the vias 411, 413, and415 and the wires 412, 414, and 416 in the chip regions 402. Inaddition, the stress absorbing walls 405 each having a multilayerstructure consisting of the buffer vias 431 a, 432 a, and 433 a and thestress absorbing walls 305 b each having a multilayer structureconsisting of the buffer vias 431 b, 432 b, and 433 b, i.e., the stressabsorbing walls 405 each having the double structure can be formedoutside the seal rings 404.

The wafer 401 thus formed with the semiconductor devices in accordancewith the method described above is diced along the scribe regions 403and thereby separated into the individual semiconductor devices(semiconductor chips). At this time, impact, a stress, a crack resultingtherefrom, or the like occurs first in the diced portion to propagatetoward each of the chip regions 402. At this time, even though the outerstress absorbing wall 405 b is destroyed by the impact, stress, crack,or the like and the impact or the like propagates toward the innerportion of the chip region 402, the impact, stress, crack, or the likeis absorbed by the stress absorbing wall 405 a located internally of thedestroyed stress absorbing wall 405 b so that the further propagation ofthe impact or the like toward the inner portion of the chip region 402is prevented successfully. This successfully prevents damage to the sealring 404 and allows the seal ring 404 to retain the function ofpreventing the ingression of moisture, movable ions, or the like intothe chip region 402 from outside thereof, which is one of the intrinsicfunctions of the seal ring 404. As a result, it becomes possible tofabricate a semiconductor device with high reliability.

According to the present embodiment, in the stress absorbing walls 405 aand 405 b in the double structure, the stress absorbing wall 405 b is ata position closest to the diced portion of a wafer, i.e., formed at aposition at most distant from the seal ring 404. Since each of thecomponents of the stress absorbing wall 405 b is smaller in length, acrack, impact, or the like that has occurred during dicing can be finelydistributed and absorbed. As a result, it becomes possible to preventdamage to the seal ring 404 and the chip region 402 when the wafer 401is divided into individual semiconductor chips and thereby prevent thedegradation of the performance of each of the semiconductor chips. Sinceeach of the components of the stress absorbing wall 405 b is smaller insize, even though the component receives a crack, impact, or the likeduring dicing and is destroyed thereby, the component easily comes offfrom the semiconductor device (one of the individual semiconductor chipsinto which the wafer has been separated). This prevents a situationwhere the destroyed component is left protruding from the end portion ofthe semiconductor chip after dicing and thereby eliminates a defectiveproduct resulting from the contact between the residue of the stressabsorbing wall 405 b and a bonding wire when packaging is performed withrespect to the semiconductor chip.

Although the present embodiment has used the multilayer structuresconsisting of the vias (the buffer vias 431 a, 431 b, 432 a, 432 b, 433a, and 433 b) as the stress absorbing walls 405 a and 405 b, it is alsopossible to use multilayer structures each consisting of vias and wires,which is similar to the multilayer structure of the seal ring 404,instead. Although the present embodiment has used the multilayerstructure consisting of the vias (seal vias 421, 423, and 425) and thewires (the seal wires 422, 424, and 426) as the seal ring 404, it isalso possible to use a multilayer structure consisting only of vias,which is similar to that of each of the stress absorbing walls 405 a and405 b. In the case where the multilayer structure consisting only of thevias is used as each of the seal ring 404 and the stress absorbing walls405 a and 405 b, a region in a widthwise direction (directionperpendicular to the direction in which the seal ring 404 extends alongthe periphery of the chip region 402) occupied by the seal ring 404 andthe stress absorbing walls 405 a and 405 b in the semiconductor devicecan be reduced compared with the case where the multilayer structureconsisting of the vias and the wires is used. This is effective inreducing the size of the semiconductor device.

In the present embodiment, at least one or more of the individualconductors (parts) that have been stacked in layers to compose each ofthe seal rings 404 are formed preferably in the step of forming thewires having the dual damascene structures. This allows the parts of theseal rings 404 to penetrate through at least one of the interlayerinsulating films without leaving seams. That is, by forming the parts ofthe seal rings 404 in the process of forming the dual damascene wires,the “seams” of each of the seal rings 404 can be reduced in the entirechip region 402 formed with the seal ring, elements such as atransistor, a wiring layer, and the like. As a result, it becomespossible to prevent the ingression of impact that has occurred duringwafer dicing or moisture from the outside into the chip region 402.

Although the present embodiment has formed the stress absorbing walls405 a and 405 b in the scribe region 403, it is not limited thereto. Thesame effect is obtainable irrespective of the positions at which thestress absorbing walls 405 a and 405 b are formed provided that thestress absorbing walls 405 a and 405 b are interposed between the dicedportion of the wafer and the seal ring 404. Specifically, the stressabsorbing walls 405 a and 405 b may also be provided outside the sealring 404, e.g., in the portions of each of the chip region 402 which areadjacent to the boundary with the scribe region 403.

Although the present embodiment has provided the seal ring 404 in theportion of each of the chip regions 402 which is adjacent to theboundary with the scribe region 403, the seal ring 404 may also beprovided internally of the stress absorbing walls 405 a and 405 b, e.g.,in the portion of the scribe region 403 which remains as the end portionof the semiconductor device (semiconductor chip) even after the dicing(i.e., the portion of the scribe region 403 which is adjacent to theboundary with the chip region 402).

Although the present embodiment has formed the wiring structure in thethree interlayer insulating films stacked in layers, the number of theinterlayer insulating films stacked in layers is not limited to 3. Itwill easily be appreciated that the number of the interlayer insulatingfilms stacked in layers may be smaller or larger than 3 depending on thechip structure.

Although the present embodiment has used Cu as a conductive material forconstituting each of the seal ring 404 and the stress absorbing walls405 a and 405 b, it is not limited thereto. It is also possible to useat least one of W, Al, and Cu to compose each of the seal ring 404 andthe stress absorbing walls 405 a and 405 b. This allows the seal ring404 and the stress absorbing walls 405 a and 405 b to be formed from thesame material as composing the wires and the vias formed in the chipregion 402 of the semiconductor device.

A description will be given herein below to variations of the seal ringstructure in each of the embodiments of the present invention by usingthe seal ring 104 according to the first embodiment as an example.However, the same shall apply to the seal rings 204, 304, and 404according to the other embodiments.

FIGS. 29A to 29F show the respective cross-sectional structures of thevariations of the seal ring structure in each of the embodiments of thepresent invention. FIGS. 30A to 30C and FIGS. 31A to 31C show the planstructures of the variations of the seal ring structure in each of theembodiments of the present invention. In FIGS. 30A to 30C and FIGS. 31Ato 31C, the seal rings 104 are indicated by the bold solid lines.

The characteristic feature of the seal ring structure shown in FIG. 29Ais that the passivation film 109 has an opening formed over the thirdseal wire 126 formed in the uppermost-layer interlayer insulating film(the third interlayer insulating film 108) and a cap layer 127 isprovided in the opening. This brings the portion of the passivation film109 located in the chip region 102 and the portion thereof locatedoutside the seal ring formation region (including the scribe region 103)into discrete relation so that mechanical impact received by the portionof the passivation film 109 which is adjacent to the scribe region 103during dicing is less likely to be transmitted to the portion of a filmsuch as the passivation film 109 deposited on the chip region 102. Thatis, since the passivation film 109 is locally discrete in the portion ofthe chip region 102 which is adjacent to the boundary with the scriberegion 103, it becomes possible to prevent the impact that has occurredduring wafer dicing from reaching the chip region 102.

The seal ring structure shown in FIG. 29B is different from the sealring structure shown in FIG. 29A in that seal vias 121 a and 121 b eachconnecting to the conductive layer 120 are provided in the firstinterlayer insulating film 106 in place of the seal via 121, that sealvias 123 a and 123 b each connecting to the first seal wire 122 areprovided in the second interlayer insulating film 107 in place of thesecond seal via 123 and the second seal wire 124, and that seal vias 125a and 125 b connecting to the seal vias 123 a and 123 b, respectively,are provided in the third interlayer insulating film 108 in place of thethird seal via 125 and the third seal wire 125. Each of the seal vias121 a and 121 b has an upper portion thereof connected to the first sealwire 122, while each of the seal vias 125 a and 125 b has an upperportion thereof connected to the cap layer 127. The seal ring structureshown in FIG. 29B provides the following effect in addition to theeffect obtainable from the seal ring structure shown in FIG. 29A. In aseal ring structure, the strength of a seal via is lower than that of aseal wire because the width of the seal via is smaller than that of theseal wire. However, by using a seal via branched into two or more parts,not a single seal via, as a part composing a seal ring as shown in theseal ring structure of FIG. 29B, a multilayer structure of seal rings (astructure multiply surrounding the chip region 102) can be implementedlocally in the interlayer insulating film provided with the branchedseal vias. Compared with a seal ring having a single seal via (i.e., ina single structure) in a given interlayer insulating film, the strengthof the seal ring structure shown in FIG. 29B having the portion in themultiple structure is improved.

The characteristic feature of the seal ring structure shown in FIG. 29Cis that a double seal ring structure composed of a seal ring 104 a and aseal ring 104 b is provided in the portion of the chip region 102 whichis adjacent to the scribe region 103 (i.e., in the seal ring formationregion). Specifically, the seal ring 104 a is composed of: a conductivelayer 120 a formed in the substrate 101; a seal via 121 a formed in thefirst interlayer insulating film 106 and connecting to the conductivelayer 120 a; a seal via 123 a formed in the lower portion of the secondinterlayer insulating film 107 and connecting to the seal via 121 a; aseal wire 124 a formed in the upper portion of the second interlayerinsulating film 107 and connecting to the seal via 123 a; and a seal via125 a formed in the third interlayer insulating film 108 and connectingto the seal wire 124 a. The seal ring 104 b is composed of: a conductivelayer 120 b formed in the substrate 101; a seal via 121 b formed in thefirst interlayer insulating film 106 and connecting to the conductivelayer 120 b; a seal via 123 b formed in the lower portion of the secondinterlayer insulating film 107 and connecting to the seal via 121 b; aseal wire 124 b formed in the upper portion of the second interlayerinsulating film 107 and connecting to the seal via 123 b; and a seal via125 b formed in the third interlayer insulating film 108 and connectingto the seal wire 124 b. The passivation film 109 has respective openingsformed over the seal vias 125 a and 125 b formed in the uppermost-layerinterlayer insulating film (the third interlayer insulating film 108)and cap layers 127 a and 127 b are provided in the respective openings.In the seal ring structure shown in FIG. 29C, seal rings 194 a and 104 beach continuously surrounding the chip region 102 are formed in a doublestructure in the peripheral portion of the chip region 102. Duringdicing, the arrangement can more reliably prevent mechanical impactresulting from the contact between the blade of a dicing system and thescribe line (scribe region) 103 from being applied to the chip region102 when the semiconductor wafer (substrate) 101 is diced along thescribe region 103 and the individual complete semiconductor chips(semiconductor devices) into which the wafer has been separated arecollected therefrom and prevent the chip region 102 from being destroyedthereby. The cap layers 127 a and 127 b formed in the respectiveuppermost portions of the seal rings 104 a and 104 b are provided in theopenings of the passivation film 109 each continuously surrounding thechip region 102. Accordingly, the passivation film 109 is doubly dividedby the cap layers 127 a and 127 b into the portion formed in the chipregion 102 and the portion formed in the scribe region 103. As a result,there is no such situation that the scribe region 103 and the chipregion 102 are connected to each other via the passivation film 109 and,therefore, the impact received by the portion of the passivation film109 located in the scribe region 103 during dicing is barely propagatedto the chip region 102 via the passivation film 109.

The seal ring structure shown in FIG. 29D is obtained by providingtherein the seal ring structure shown in FIG. 29B in a doubleconfiguration, similarly to the seal ring structure shown in FIG. 29C.The seal ring structure shown in FIG. 29D can also achieve the sameeffect as achieved by the seal ring structure shown in FIG. 29B inaddition to the same effect as achieved by the seal ring structure shownin FIG. 29C.

In the seal ring structure shown in FIG. 29C, the openings need not beformed in the passivation film 109 and the cap layers 127 a and 127 bneed not also be provided, as shown in FIG. 29E. It is also possible toprovide either one of the cap layers, though it is not depicted.

In the seal ring structure shown in FIG. 29D, the openings need not beformed in the passivation film 109 and the cap layers 127 a and 127 bneed not also be provided, as shown in FIG. 29F. It is also possible toprovide either one of the cap layers, though it is not depicted.

The characteristic feature of the plan configuration of the seal ringstructure shown in FIG. 30A is that the seal ring 104 has rectangularprojections/depressions when viewed from above the substrate 101 (i.e.,the passivation film 109).

The characteristic feature of the plan configuration of the seal ringstructure shown in FIG. 30B is that the seal ring 104 has triangularprojections/depressions when viewed from above the substrate 101.

The characteristic feature of the plan configuration of the seal ringstructure shown in FIG. 30C is that the side portions of the seal ring104 is provided with a plurality of projections each extending towardthe scribe region 103. In other words, the seal ring 104 has theplurality of projections in directions perpendicular to the direction inwhich the scribe region 103 extends.

The respective cross-sectional configurations of the semiconductordevices corresponding to FIGS. 30A to 30C are the same as in the firstembodiment shown in FIG. 2 or in the above-mentioned variations shown inFIGS. 29A and 29B, except that the position at which the seal ring 104is formed varies in a horizontal direction or the width of the seal ring104 varies depending on a position from which the cross section isobserved.

In the semiconductor device having the seal ring structure shown in anyof FIGS. 30A to 30C, the barrier of each of the seal rings 104protecting the chip regions 102 is provided not only in a directionparallel to the direction in which the scribe region 103 extends butalso in directions perpendicular and oblique thereto. The arrangementcan prevent impact and a stress each resulting from the contact betweenthe blade of the dicing system and a film such as the passivation film109 during wafer dicing, a crack caused thereby in the wafer (substrate101), and the like from propagating along the side surface (the surfaceopposing the scribe region 103) of the seal ring 104.

The characteristic feature of the plan configuration of the seal ringstructure shown in FIG. 31A is that the side portion of the seal ring104 opposing the scribe region 103 has rectangularprojections/depressions when viewed from above the substrate 101 (i.e.,the passivation film 109).

The characteristic feature of the plan configuration of the seal ringstructure shown in FIG. 31B is that the side portion of the seal ring104 opposing the scribe region 103 has triangularprojections/depressions when viewed from above the substrate 101.

The characteristic feature of the plan configuration of the seal ringstructure shown in FIG. 31C is that the side portion of the seal ring104 b opposing the scribe region 103 is provided with a plurality ofprojections each extending toward the scribe region 103. In other words,the seal ring 104 b has a plurality of projections in directionsperpendicular to the direction in which the scribe region 103 extends.

The respective cross-sectional structures of the semiconductor devicescorresponding to FIGS. 31A to 31C are the same as in the above-mentionedvariations shown in FIGS. 29C to 29F, except that the position at whichthe seal ring 104 is formed varies in a horizontal direction or thewidth of the seal ring 104 varies depending on a position from which thecross section is observed.

The semiconductor device having the seal ring structure according to thepresent embodiment shown in any of FIGS. 31A to 31C achieves thefollowing effect in addition to the same effect achieved by the doubleseal ring structure in any of the variations shown in FIGS. 29C to 29F.Of the seal rings 104 a and 104 b protecting the chip regions 102, eachof the seal rings 104 b has a barrier opposing the scribe region 103which is provided not only in a direction parallel to the direction inwhich the scribe region 103 extends but also in directions perpendicularand oblique thereto. The arrangement can prevent impact and a stresseach resulting from the contact between the blade of the dicing systemand a film such as the passivation film 109 during wafer dicing, a crackcaused thereby in the wafer (substrate 101), and the like frompropagating along the side surface (the surface opposing the scriberegion 103) of the seal ring 104 b.

The description has been given to the combination of the seal ring 104 ahaving a linear plan configuration and the seal ring 104 b having a planconfiguration other than the linear plan configuration in each of theseal ring structures (double structures) shown in FIGS. 31A to 31C.However, both of the seal rings 104 a and 104 b may have planconfigurations (which may be the same or different from each other)other than the linear configuration. It is also possible to use a sealring structure in a triple or higher-order multiple configuration, ofwhich at least the outermost seal ring has a plan configuration otherthan the linear configuration. In the case where a plurality of sealrings having plan configurations other than the linear configuration areused or where a seal ring structure having a triple or higher-ordermultiple configuration is used, the width ratio of the seal ring portionto the whole semiconductor device (semiconductor chip) may be increaseddisadvantageously in terms of the size reduction of the semiconductordevice. Accordingly, it is preferable to use a double seal ringstructure obtained by combining a seal ring having a linear planconfiguration with a seal ring having a plan configuration other thanthe linear plan configuration, such as the seal ring structure shown ineach of FIGS. 31A to 31C.

1. An electronic device comprising: a substrate; a multilayer structurecomposed of a plurality of interlayer insulating films formed on thesubstrate; a seal ring structure formed to contact the substrate, toextend through the multilayer structure which is located in a peripheralportion of a chip region and to continuously surround the chip region;and stress absorbing walls in a double or higher-order multiplestructure formed to extend through the multilayer structure which arelocated outside the seal ring structure viewed from the chip region andto discretely surround the entirety of the seal ring structure in a planview, wherein each of components of one of the stress absorbing walls inthe double or higher-order multiple structure which is formed at aposition most distant from the seal ring structure has a shorter lengthalong a direction in which the seal ring structure extends than each ofcomponents of the other stress absorbing wall or walls.
 2. Theelectronic device of claim 1, wherein gap portions between respectivediscrete portions of each of the stress absorbing walls in the double orhigher-order multiple structure are not aligned in rows.
 3. Theelectronic device of claim 1, wherein each of the seal ring structureand one of the stress absorbing walls is composed of at least one of W,Al, and Cu.
 4. The electronic device of claim 1, wherein: a piece of oneof the stress absorbing walls has a substantially rectangular shapehaving a long side and a short side which is shorter than the long side,and the long side of the stress absorbing wall is provided in adirection parallel to one side of the seal ring structure.
 5. Theelectronic device of claim 1, wherein the seal ring structure has asubstantially planar shape with a winding in a portion corresponding toone side of the chip region.
 6. The electronic device of claim 1,wherein the seal ring structure has a substantially planar shape with aprojection extending to the opposite side of the chip region in aportion corresponding to one side of the chip region.
 7. The electronicdevice of claim 1, wherein the seal ring structure is in a double orhigher-order multiple configuration.
 8. The electronic device of claim1, wherein: a piece of at least one of the stress absorbing walls has asubstantially rectangular shape having a long side and a short sidewhich is shorter than the long side, and a length of the long side islonger than a distance between said piece and another piece adjacent tosaid piece.
 9. The electronic device of claim 1, wherein the stressabsorbing walls are located outside the seal ring structure but are notlocated inside the seal ring structure viewed from the chip region.